Function
A surge protector is a device used to protect electronic equipment such as computers and game consoles from power surges. Excess voltage from a power surge will be redirected into a grounding wire and thus prevented from reaching your PS3.
Features
Most surge protectors come with multiple outlets to plug in several devices at once. More complex---and often more expensive---surge protectors also have outlets for phone cords and coaxial cables. These additional features will not benefit your PS3.
Warranties
Many surge protectors come with a limited warranty or guarantee that covers any power surge damage sustained by your PS3 while plugged into the protector. If the surge protector you're thinking about buying does not offer a warranty, it might be worth upgrading to one that does.
Considerations
Both the Xbox 360 and Nintendo Wii support sites suggest that you not use a surge protector with those consoles. Sony recommends only that you use a polarized three-prong outlet that is properly grounded for your PS3.
Misconceptions
In 2007, one PS3 owner was told by Sony customer support that using a surge protector voided the console's warranty. According to Sony, using a surge protector with your PS3 will not void the console's warranty.